A. K. Salman

Genotoxic studies in hypertensive and normotensive rats treated with amiodarone

Amiodarone, a benzofuran derivative, is a very effective antiarrhythmic medication, but has potential to cause side effects. Although its cytotoxicity potential is very well-known, there are few reports about its genotoxicity effects. Since amiodarone has not been investigated in genotoxicity studies, and the spontaneously hypertensive rat (SHR) is a well-characterized model for hypertension, the aim of the present study was to perform cytogenetic analysis on chromosome aberrations in bone marrow cells of SHRs and normotensive Wistar-Kyoto rats (WKYs) that received oral amiodarone treatment for 4 weeks. Amiodarone activity was also monitored using electrocardiograms. The presence of bradycardia in amiodarone-treated rats confirmed that this drug was really active. Metaphase analysis on bone marrow cells showed that there were significant differences in total chromosomal damage and percentage abnormal metaphase between WKY and SHR negative controls. In the SHR negative control, the frequencies of basal chromosomal aberrations and abnormal metaphases were significantly higher (p<0.05). There were high numbers of chromosomal aberrations in all amiodarone-treated groups, compared with negative controls. In amiodarone-treated groups, the most frequent chromosomal aberration was chromatid breaks. More chromosomal aberrations were found in WKYs that received amiodarone, with a statistically significant difference in comparison with negative controls (p<0.05). However, in SHR rats there was no significant difference between the amiodarone and negative groups regarding chromosomal damage induction. These results showed that treatment with amiodarone was genotoxic in WKYs, but not in SHRs. Further studies are needed to confirm whether amiodarone is genotoxic or efficient and harmless, among humans undergoing therapy.

Characterization and polymorphism screening of IGF-I and prolactin genes in Nelore heifers

Abstract Insulin growth factor I (IGF-I) and prolactin (PRL) are peptide hormones that exert complementary effects on reproductive traits by acting on folliculogenesis. In view of the lack of information about the IGF-I and PRL genes in Bos indicus, the objective of this study was to partially characterize the promoter regions of these genes and to screen animals of different ages at first pregnancy for the presence of polymorphisms in these regions. In addition, we determined whether polymorphisms influence the regulation of the two hormone genes, evaluating their association with sexual precocity. The animals were divided into three groups according to age at first pregnancy: 1) 100 heifers considered to be sexually precocious that became pregnant at 15-16 months of age, 2) 100 heifers that became pregnant during the normal breeding season at 24 months of age, and 3) 100 heifers that did not become pregnant until 24 months of age. For the IGF-I gene, PCR-RFLP-SnaBI analysis showed the presence of genotypes AB and BB at frequencies of 0.02 and 0.98, respectively. Sequencing of the IGF-I gene fragment revealed a single nitrogen base change from cytosine to thymine, corresponding to the restriction site of SnaBI. The polymorphisms identified in the 5’-flanking region of the IGF-I gene may serve as a basis for future studies of molecular markers in cattle. For the PRL gene, PCR-RFLP-HaeIII analysis showed the presence of only one migration pattern, a finding characterizing the region studied as monomorphic. The study of other regions in the IGF-I and PRL genes might provide molecular data that can be used in the future for the selection of sexually precocious animals.

Reforestation feasibility in area formerly used for cattle rasing in the state of Rondônia, Northwest Brazilian Amazon

Little knowledge on initial behavior of native tree species in recovering landscapes in the Amazon is a current concern for expanding reforestation in the region. Thus, the aim of this study was to evaluate the establishment of native tree species that could be used for reforestation in area previously covered by a pasture of brachiaria grass (Brachiaria brizantha) destined for intensive cattle rasing in the State of Rondonia. For this, there were performed previous diagnostic of landscape changes and the election of tree species based on the ecological group information. Some of the critical macronutrients for plant growth were supplied in the holes to alleviate nutrient deficiencies. In addition, growth and survival parameters were taken to evaluate the initial behavior of species. Six native tree species planted with different combinations (10mx10m, 5mx5m and 3mx3m) had survival rate and growth (total height, girth stem and crown projection area) measured in different intervals: 6-month, 12-month and 24-month after planting. All the species presented survival rate over 90% at 24 months and comparable growth indices to other native species under similar situation and in the region. Overall, Schizolobium amazonicum (bandarra), the non-identified legume tree 1 (acacia grande) and Colubrina glandulosa (sobrasil) averaged over 90% the highest girth stem growth all over the area. S. amazonicum and the non-identified legume tree 1 (acacia grande) presented the best results for height and canopy area growth parameters, respectively. The combination among native tree species from initial successional ecological groups and fertilizer was favorable to promote reforestation in the conditions of the study area in Rondonia.

Impactos ambientais do manejo agroecológico da caatinga no Rio Grande do Norte

O objetivo deste trabalho foi avaliar os impactos ambientais do manejo agroecologico da caatinga, em unidades de producao familiar no Rio Grande do Norte, pelo metodo Ambitec de producao animal - dimensao ambiental, desenvolvido pela Embrapa Meio Ambiente. Foram avaliadas sete unidades de producao familiar, em quatro projetos de assentamentos de reforma agraria do Municipio de Apodi, RN. Os dados para o levantamento foram obtidos por meio de questionarios aplicados aos representantes das unidades produtivas familiares, que atribuiram, a cada variavel estudada, um valor que representou a alteracao proporcionada pela implementacao da tecnologia. Apos a insercao dos coeficientes de alteracao de cada variavel dos indicadores por unidade de producao, o coeficiente de impacto foi automaticamente calculado por meio da planilha Ambitec. O manejo agroecologico da caatinga resultou num impacto ambiental positivo, e suas maiores contribuicoes foram relacionadas aos efeitos positivos dos seguintes indicadores: capacidade produtiva do solo, uso de insumos materiais, qualidade do produto e diminuicao da emissao de poluentes a atmosfera. Dois indicadores geraram efeitos negativos: o uso de energia e o uso de recursos naturais. Pela superioridade dos beneficios gerados, o manejo agroecologico da caatinga e uma inovacao tecnologica geradora de impactos ambientais positivos.

Relationship between thermal comfort indices and internal temperature of grazing lactating Holstein × Gyr cows in western Amazonia

The relationship between the indices of thermal comfort and internal temperature in lactating cows was evaluated inRondônia, western Amazonia in a 2 × 2 crossover trial carried out with eight Girolando cows, 1⁄2 Holstein × 1⁄2 Gyr (n=4) and 3⁄4 Holstein × 1⁄4 Gyr (n=4), grazing palisade grass supplemented with or without soybean oil concentrates. Data logger thermometers adapted to intravaginal devices (hormone free) were used to measure internal temperatures (IT) every 10 min over 48 h. Concomitantly, environmental parameters (air temperature, relative humidity, wind speed, and solar radiation) were collected for the estimation of the temperature-humidity index (THI), equivalent temperature index (ETI), and predicted respiratory rate (PRR). Supplementation with soybean oil did not affect the internal temperature of the cows. IT varied significantly between the genetic groups, with the highest mean observed at night in the 3⁄4 Holstein × 1⁄4 Gyr cows, compared with that in the 1⁄2 Holstein × 1⁄2 Gyr cows (39.54 °C vs 39.06 °C, respectively). THI, ETI, and PRR were significantly and positively correlated with the IT of the Girolando cows; however, the PRR was not found to be adequate in indicating the night-time heat stress in cows.

Degradabilidade ruminal e digestibilidade intestinal da proteína de capim-elefante com três idades de corte

The potential degradability (PD) and intestinal digestibility of ruminal escape protein (IDREP) of elephant-grass at 30, 45, and 60 days of regrowth were determined and the mobile bag technique (in situ) was compared to the three-stage method (in vitro). Thus, six cross-bred steers with rumen and duodenum canulas were used and fed exclusively with chopped elephant grass. The degradability trial was carried out with grass samples incubated in rumen by 3, 6, 9, 12, 24, 48, 72, 96, and 120 h. The intestinal digestibility was determined using 24-h ruminal incubation residue. In the in situ technique, residues in nylon bags were placed in duodenum and recovered in feces. In the in vitro method, residues were digested with solution of HCl-pepsin-pancreatin. In samples of grass at 30, 45, and 60 days of age, the values of protein PD were 87.5, 87.8, and 83.8%, respectively. The IDREP ranged with grass age and it was similar between in situ and in vitro methods only for 60-day old grass. Considering the changes in elephant-grass chemical composition due to aging, the in situ method supplied a more coherent estimative of intestinal digestibility.

Consumo de capim-elefante com diferentes idades fornecido para vacas leiteiras

The 30, 45 and 60 day-old elephant grasses were evaluated by monitoring their nutritional profile and DM (DMI) and NDF (NDFI) intake by crossbred lactating cows in a 3 x 3 Latin square trial, where the split-plots were the rumen evacuation times: 0, 2, 4 and 6 h after meal. Chemical composition, in vitro dry matter digestibility and ruminal content ranged with grass age. Means (in kg/cow/day) of DMI and NDFI of 30 day-old grass (8.0 and 5.3) were lower than those of grasses with 45 days (10.0 and 6.6) and 60 days (11.0 and 7.3). The maximum of rumen fill was observed at 4:22, 3:55 and 3:49 hours after feeding for treatments with 30, 45 and 60 day-old elephant grass, respectively. Rumen fill did not limit the DMI and NDFI of elephant grass, but the dry matter intake of 30 day-old grass may be affected by the wet content.